Comparison between invasive measurement and echocardiographic estimation of pulmonary artery pressures in end stage liver disease patients with portopulmonary hypertension

Introduction. Severe porto-pulmonary hypertension (PoPH) associated with end stage liver disease (ESLD) has a high morbidity and mortality¹. Transthoracic echocardiographic estimation of right ventricular systolic pressure (RVSP) using continuous wave Doppler blood flow velocity of tricuspid regurgitation and the modified Bernouilli equation (ΔP=4v²) has been shown to be accurate². Arbitrarily, a right atrial pressure (RAP) of 10 mmHg is assumed. The effect of a hyperdynamic circulation associated with ESLD and PoPH on echocardiographically-derived data is not known. Methods. We investigated the agreement between noninvasive estimations of RVSP and invasive measurement using right heart catheterization in ESLD patients with pulmonary hypertension who were candidates for liver transplantation. We searched our databases for patients with a diagnosis of ESLD and pulmonary hypertension (PHTN) from 1989 until the present. We excluded all patients who had another possible cause of PHTN, those receiving PGI₂, and those who were anesthetized when data were obtained. The procedures were not performed simultaneously. We identified a subgroup of 17 patients. Results. Echocardiography (mmHg) Right heart catheterization (mmHg) RVSP 50+/-20 45+/-20 Mean RAP 9+/-6 Mean pulmonary artery pressure 30+/-14 Cardiac output 6.7+/-2.4 Pulmonary artery occlusion pressure 11+/-5 The group's mean hemodynamics reflect a population of ESLD patients with mild to moderate PoPH (MPAP > 25 mmHg) without fluid overload. We performed a Bland-Altman analysis to measure agreement³. We determined the mean of differences or bias to be + 8 mmHg and the limits of agreement (mean+/- 1.96x SD of differences) to be -10 to +27 mmHg. Conclusion. This nonsimultaneous preliminary analysis shows there is a bias for overestimation of echocardiographically-derived RVSP compared with invasively measured pulmonary artery pressure data. These methodological differences may be important for the clinical evaluation of ESLD patients with PoPH.